Temperature conversion

Celsius to Kelvin conversion

Celsius to Kelvin conversion. Exact conversion factors, worked examples, and privacy-first browser calculation on CalculatorX. Fast and free.

Instant result

Result

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Formulas

Core equations used by this converter.

°C → KK = °C + 273.15

Exact anchors0 °C = 273.15 K

K → °C°C = K − 273.15

iTemperature conversions are affine (scale + offset), not a single multiply. Absolute zero is 0 K = −273.15 °C = −459.67 °F = 0 °R.

How to use

1

Choose °C → K or K → °C

Use the tabs to switch direction. Forward mode needs celsius; reverse uses the opposite unit.

2

Enter the temperature

Type a signed value in the active unit field.

3

Convert and read the result

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Example conversions

Common values with formula and result.

ϟ

0 °C to Kelvin (water freezes)

0 °C to Kelvin (water freezes)

0 + 273.15 = 273.15 K

273.15 K

ϟ

20 °C to Kelvin (room temperature)

20 °C to Kelvin (room temperature)

20 + 273.15 = 293.15 K

293.15 K

ϟ

100 °C to Kelvin (water boils at 1 atm)

100 °C to Kelvin (water boils at 1 atm)

100 + 273.15 = 373.15 K

373.15 K

ϟ

−273.15 °C to Kelvin (absolute zero)

−273.15 °C to Kelvin (absolute zero)

−273.15 + 273.15 = 0 K

0 K

Celsius to Kelvin conversion specification

Version 1.1.0 · Engine tested

Calculation status

Engine tested 4 published cases
Named expert review Not performed
Calculation version 1.1.0

Definition: **Celsius (°C)** — everyday metric temperature; water freezes at **0 °C**, boils at **100 °C** (1 atm). **Kelvin (K)** — SI base unit of thermodynamic temperature; **0 K** is absolute zero. A change of 1 K equals a change of 1 °C.
What it calculates: Temperature between °C and K. Switch direction with the converter tabs.
Inputs: Celsius (°C) or reverse unit (K)
Outputs: Converted value in K or °C
Formula: K = °C + 273.15 · °C = K − 273.15
Celsius to Kelvin conversion table: Celsius (°C) Kelvin (K) Notes
−273.15 °C 0 K Absolute zero
−40 °C 233.15 K
−20 °C 253.15 K
0 °C 273.15 K Water freezes
10 °C 283.15 K
20 °C 293.15 K Room temperature
25 °C 298.15 K Standard lab (approx.)
37 °C 310.15 K Body temperature
100 °C 373.15 K Water boils (1 atm)
Assumptions: Conversion runs locally in the browser; values are not uploaded.
Uses the standard factor/definition for these units.
Units: °C → K
K → °C
Boundary conditions: Empty or non-numeric input yields no valid result.
Negative temperatures are allowed.
Example: 0 °C → 273.15 K
Validation cases: 0 °C → 273.15 K
20 °C → 293.15 K
37 °C → 310.15 K
100 °C → 373.15 K
Sources: ITS-90 / SI temperature scale definitions (°C, K)
Fahrenheit defined relative to Celsius: °F = °C × 9/5 + 32
Calculation version: 1.1.0

Background

Interpretation and common distinctions.

Use the converter tabs to switch direction when available. Results for Celsius to Kelvin conversion update locally in your browser.

Frequently asked questions

Key distinctions behind the conversion.

Is Kelvin the same size as Celsius?

Yes. A 1 °C change equals a 1 K change. Only the zero points differ.

Why add 273.15?

Absolute zero is **−273.15 °C**, so Kelvin shifts the scale so that absolute zero is **0 K**.

Do I write °K?

No. The correct symbol is **K** (kelvin), without a degree sign.

How do I convert Kelvin back to Celsius?

**°C = K − 273.15**. See [Kelvin to Celsius](/convert/temperature/kelvin-to-celsius).